General-purpose engines used in industry usually have a centrifugal-type mechanical governor unit to hold down the maximum r.p.m. and maintain the minimum r.p.m. as needed. A mechanical governor unit of this sort converts to torque the centrifugal force generated by a flyweight as the crankshaft of the engine rotates. It outputs this torque mechanically to the exterior and compares it with the attendant force of the governor spring, which has been established previously. If the torque resulting from the centrifugal force exceeds the force of the spring, the governor unit operates the engine throttle to decrease the flow of the gas mixture and reduce the engine output. In this way the engine speed can be kept within specified bounds. Because this adjustment must be made while the engine is running, the throttle operating panel for an engine with this sort of governor unit must be easy to adjust. It must also be covered so as to prevent foreign matter from coming in contact with the operating panel.
Two configurations which have been proposed for the operating panel of a general-use single-cylinder engine with this type of governor unit are disclosed in the Japanese Patent Publication 6-40329 and 3-65827.
FIG. 6 is a frontal view of the general-use engine proposed in Patent Publication 6-40329.
In FIG. 6, 01 is the (entire) engine; 02 is the main portion of the said engine 01, including the crankcase. On the front of the said engine body 02 are fan cover 03, formed from a metal plate, and recoil starter 04, which starts the engine. 07 is the fuel tank, installed on top of engine body 02. 023 is the air cleaner.
In engine 01, throttle control 024, which controls the speed of the engine, is placed on top of carburetor and air cleaner 023. Cover 035 encloses the entire engine in order to keep it clean. This configuration makes it easy to run wiring from the exterior of the engine to lever 028, which controls the speed. It will also prevent the operation of the engine from being affected by another unit outside engine body 02. This design makes it easier to connect or disconnect a wire to speed lever 028.
In the configuration proposed in Patent Publication 3-65827, the throttle operation panel is located below the fuel tank in the space between the bottom of the fuel tank and the top of the fan cover. The components which constitute the operating panel are covered from the front. Holes are provided in the appropriate parts of the cover of the said operating panel for the throttle lever, the choke lever and the adjacent engine switch.
In the prior art engines described above, the fuel pipe runs along the side of either the cylinder (i.e., the engine body) or the fan cover. It is secured by means of clamps and bolts.
With the configuration proposed in Patent Publication 6-40329, the throttle control 024 is mounted on support plate 025, which itself is mounted on engine body 02 by a number of bolts. These components are protected by front cover 035. This configuration, then, requires a large number of parts, including the support plate, the bolts for the mounting surface, and the front cover. As a result, the parts count is extremely high.
With the configuration proposed in Patent Publication 3-65827, the throttle control (i.e., the governor unit) is simply covered by an operating panel. No improvements are made with regard to the interrelationship of the operating levers with the governor unit and the carburetor. In addition, the fuel pipe is mounted so that it runs along the side of either the engine body or the fan cover and it is secured to the engine body by means of clamps and bolts, which greatly increases the parts count.